Electronic transmission lines that connecting electronic devices or components may be affected by electromagnetic interferences (EMI). The EMI may cause electronic noise that distorts the signal and decreases sensitivity. To reduce the effects of EMI and other undesirable noises, coaxial cables are usually used as transmission lines.
A coaxial cable is one that consists of two conductors that share a common axis. The inner conductor is typically a straight wire, either solid or stranded and the outer conductor is typically a shield that might be braided or a foil. Coaxial cables are typically characterized by the impedance and cable loss. The characteristic impedance is determined by the size and spacing of the conductors and the type of dielectric used between them. A coaxial cable provides protection of signals from external electromagnetic interference, and effectively guides signals with low emission along the length of the cable. Although coaxial cables have been used to provide shielded connections for electronic devices and components, such shielded connections do not exist for printed electronic circuits.